package com.huawei;

/**
 * Created by Z-hong on 2024/7/25.
 */
import java.util.*;
public class HJ107 {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        String d= sc.next();
        boolean flag=true;
        if(d.charAt(0)=='-'){flag=false;d=d.substring(1);}
        double f=0.1;
        while(true){
            double res=f*f*f;
            String s=String.format("%.1f",res);
            if(d.equals(s)){
                if(flag){
                    System.out.printf(String.format("%.1f",f));
                }else{
                    System.out.printf(String.format("-%.1f",f));
                }

                break;
            }else if(Double.parseDouble(d)<res){
                double temp=f-0.1;
                double temp_3=temp*temp*temp;
                if(Math.abs(Double.parseDouble(d)-temp_3)<Math.abs(res-Double.parseDouble(d))){
                    if(flag){
                        System.out.printf(String.format("%.1f",temp));
                    }else{
                        System.out.printf(String.format("-%.1f",temp));
                    }
                }else{
                    if(flag){
                        System.out.printf(String.format("%.1f",f));
                    }else{
                        System.out.printf(String.format("-%.1f",f));
                    }                }
                break;
            }
            f+=0.1;
        }
    }
}
